The ringleader behind Mark Fisher’s murder didn’t just order the teen’s death – but helped “rob, beat and shoot” him on a Brooklyn street, prosecutors said yesterday.

The 6-foot-5 Fisher was too powerful for Antonio Russo to handle alone, so John Guica – and, most likely, a third person – attacked the Fairfield University football player, said Assistant District Attorney Anna-Sigga Nicolazzi.

“Mark Fisher was ultimately a lamb surrounded by wolves,” Nicolazzi said of the Andover, N.J., teen who was drunk, lost and almost out of cash after a night of barhopping on the Upper East Side led him to a party at Guica’s Ditmas Park home on Oct. 12, 2003.

During her closing argument, Nicolazzi showed the jury a photo of Fisher’s bullet-riddled body face down in a pool of his own blood.

“This case begins, continues and ends with John Guica,” the prosecutor said.

Guica – the reputed head of a fledgling street gang – orchestrated the robbery and the stonewalling of investigators, according to testimony from one of his friends and his ex-girlfriend.

But Guica’s lawyer, Samuel Gregory, claimed that those witnesses lied and gave conflicting accounts.

Jonathan Fink, who represents Russo, noted that the .22-caliber murder weapon was never found and tried to lay the blame squarely on Guica, saying, “He’s the person you have to look at in this case to see where guilt lies.”

Juries for both Guica and Russo are expected to begin deliberating today.